Factor VIII/von Willebrand factor (f.VIII/vWf) protein appears necessary for promotion of platelet adhesion to the collagen contained in the subendothelium. The exact nature of the f.VIII/vWf protein-collagen interaction remains unclear. This study is intended to examine this interaction and to determine whether there exists a f.VIII/vWf protein functional heterogeneity with collagen interaction as there is with platelet interactions. An efficient technique has been examined to assess adsorption of f.VIII/vWf activities to purified genetic type 1 collagen and then to analyze the multimeric structue of the unadsorbed and adsorbed f.VIII/vWf protein via glyoxylagorose electrophoresis and auto-radiography with a purified anti-VIII R:Ag.